ALP dark matter with non-periodic potentials: parametric resonance, halo formation and gravitational signatures

Understand

Axion-like particles (ALPs) are leading candidates to explain the dark matter in the universe.

• Their production via the misalignment mechanism has been extensively studied for cosine potentials characteristic of pseudo-Nambu-Goldstone bosons.
• In this work we investigate ALPs with non-periodic potentials, which allow for large misalignment of the field from the minimum.
• As a result, the ALP can match the relic density of dark matter in a large part of the parameter space.